1. Field of the Invention
The present invention relates in general to the field of test probes and pertains, more particularly, to a test probe with a flexible conductive pad at the end of the test probe for testing electrical circuits.
2. Background Discussion
FIG. 1 shows an embodiment of a prior art test probe. The test probe 10 is comprised of a conductive material 12 attached to a pin 14 which is attached to the tester 16. The test probe 10 tests circuits, pads, leads, etc., by being lowered onto the device to be tested. In FIG. 1 the test probe 10 tests a circuit 18 by the conductive material 12 making contact with the circuit. This testing is performed either by a number of pins 14 attached to the tester 16 and arranged in an array or bed of nails scheme, or by having only one pin 14 attached to the tester 16. The former scheme generally is an automated process where the array of test probes attached to a tester are lowered onto a circuit and the test probes simultaneously test a number of circuits. The latter scheme generally is a manual testing process wherein the test probe tests only one point of a circuit at a time.
The problem with the prior art means for testing circuits is the hardness of the conductive material at the end of the pin. Being a solid conducting material, the end of the test probe is very hard and can damage the circuit being tested. The damage occurs due to the force applied to the circuit by the test probe which makes contact with the circuit. This problem is particularly prevalent in environments where the circuits being tested are very small and fragile.
Another problem with the prior art is that the conductive material on the end of the pin can be damaged or broken off with excessive use and force being applied to it in contacting circuits. These above mentioned problems are equally prevalent in the use of high-speed automatic test probes, and hand-held manual test probes.
A prior art method which attempted to alleviate these problems can be described in conjunction with FIG. 1. A spring is placed inside of a hollow pin 14 and attached to the conductive material 12. When the conductive material 12 contacts a circuit 18, the spring compresses, thus lessening the amount of force applied to the circuit.
Although this method alleviated some of the problems of damaged circuits, it is not a practical solution because it cannot be used for testing small circuits because this type of testing requires the use of a pin the size of a wire, which would be too small to encase a spring inside of it. In addition, this test probe did not alleviate the damage to the circuits caused by the conductive material scraping the circuit. Being a hard conductive metal, this material was prone to not only crush but to scrape circuits if the material, when in contact with the circuit, was moved along the circuit.